An interactive tool someone would use twice

Use with: build-website. Resume line when done: Built and deployed {project_name}, an interactive {tool_kind} — live at {url}

Brief

One genuinely useful calculator, converter, or tracker with state and input validation. Useful means you or someone you know would open it a second time without being asked. Single page, deployed, works on a phone.

Personalize

• The itch. What do you currently work out on paper, in a notes app, or badly in your head? Grade needed on the final to pass, split costs for a trip, rep-weight progression, commute timing: yours will be better because it is yours.
• The second user. Name the person who would use it twice. You will show them milestone 4.

Milestones

1. The math or logic written out in the README as plain sentences before any code.
2. Ugly version live: inputs, output, no styling.
3. Input validation: wrong input gets a message, never a wrong answer.
4. The second user tries it. What confused them gets fixed.
5. Styling: phone-first, clear labels, the result impossible to misread. Final README.

Done means

• Live URL responding; works on a phone screen
• Correct results, validated inputs, no dead states
• Second user's test and the fix it caused noted in the README
• At least 8 commits across at least 5 distinct days, authored by you
• SESSIONS.md has an entry per session, written by you